Alignment system for multiple branch endografts

ABSTRACT

A nonmodular endograft system for treating aortic aneurysms involving bilateral renal arteries can include a main fabric cover that is sealedly coupled, or integral, with first and second branch fabric covers. The system can be configured so that after the main cover is expanded in the aorta, and after the two branch covers are respectively expanded in the renal arteries such that (i) the first cover ostium is substantially aligned with the first renal ostium, and (ii) the second cover ostium is not substantially aligned with the second renal ostium, then aortic blood flows from the main cover into each of the branch covers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/684,282 (Attorney Docket No. 50001-705.201), filed Apr. 10, 2015, nowU.S. patent Ser. No. ______, which claims priority from U.S. ProvisionalApplication No. 61/978,772 (Attorney Docket No. 50001-705.101), filed onApr. 11, 2014, the entire content of which are hereby incorporated byreference.

FIELD OF THE INVENTION

The subject technology relates generally to implantable devices forinterventional therapeutic treatment and, more particularly, to a branchendograft and delivery system for the treatment of disease involvingbranching vessels.

BACKGROUND OF THE INVENTION

Endoluminal repair or exclusion of aneurysms, such as in the aorta, hasbeen performed in recent years. Endoluminal aortic aneurysm exclusioncan correct a life-threatening disease in a minimally invasive manner inorder to effectuate a patient's quick and complete recovery. Variousvascular grafts exist that have been used to exclude aortic aneurysms.

The aorta is the largest artery in the body and is responsible fordelivering blood from the heart to the organs of the body. The aortaincludes the thoracic aorta, which arises from the left ventricle of theheart, passes upward, bends over and passes down towards the thorax, andthe abdominal aorta which passes through the thorax and through theabdomen to about the level of the fourth lumbar vertebra, where itdivides into the two common iliac arteries. The thoracic aorta isdivided into the (i) ascending aorta, which arises from the leftventricle of the heart, (ii) the aorta arch, which arches from theascending aorta and (iii) the descending aorta which descends from theaorta arch towards the abdominal aortic.

A thoracic aortic aneurysm (“TAA”) is a widening, bulge, or ballooningout of a portion of the thoracic aorta, usually at a weak spot in theaortic wall. If left untreated, the aneurysm may progressively expanduntil the vessel dissects or ruptures. This may lead to severe and evenfatal hemorrhaging. Factors leading to thoracic aorta aneurysms includehardening of the arteries (atherosclerosis), hypertension, congenitaldisorders such as Marfan's syndrome, trauma, or less commonly syphilis.Thoracic aorta aneurysms occur in the ascending aorta about 25% of thetime, the aortic arch about 25% of the time and in the descending aortaabout 50% of the time.

Treatment of thoracic aorta aneurysms depends upon the location of theaneurysm. For aneurysms in the ascending aorta or aortic arch, surgeryis typically required to replace the aorta with an artificial vessel.This surgical procedure typically requires exposure of the aorta and theuse of a heart-lung machine. If the aortic arch is involved, aspecialized technique called “circulatory arrest” (i.e., a periodwithout blood circulation while on life support) may be necessary. Foraneurysms in the descending aorta, the vessel may also be replaced withan artificial vessel through surgery. In some circumstances, anendoluminal vascular graft may be used eliminating the need for opensurgery.

Straight tube grafts have been used in the infrarenal abdominal aorta toexclude an aneurysmal sac from the blood stream, thereby resulting inthe weakened aortic wall being protected by graft material. Thesestraight tube grafts were initially unsupported; they employed stents attheir proximal and distal ends to anchor the proximal and distal ends ofthe graft to the healthy portions of the aorta thereby leaving amidsection of the graft or prosthesis that did not have any internalsupport. Although this type of graft at first appeared to correct theaortic aneurysm, it met with many failures. The unsupported nature ofits midsection allowed the graft to migrate distally as well as exhibitsignificant proximal leakage due to the enlargement of the aorta withoutadaptation of the graft, such as enlargement of the graft, toaccommodate the change in diameter of the aorta.

Technical improvements in stent design led to “self-expanding” stents.In addition, later improvements produced Nitinol stents which have a“memory” capable of expanding to a predetermined size. Graft designersbegan to develop bifurcated grafts having limbs which extended into theiliac arteries. The development of bifurcated grafts allowed for thetreatment of more complex aneurysms.

Many bifurcated grafts are of a two-piece or modular design. Thetwo-piece designs often require the insertion of a contralateral limbthrough or a separate access site. These types of grafts are complex todeploy and have the potential for leakage at the connection site of thetwo limbs of the graft.

Endoluminal implantation is a common technique for implanting vasculargrafts. Typically, this procedure involves percutaneously inserting avascular graft or prosthesis by using a delivery catheter. This processeliminates the need for major surgical intervention, thereby decreasingthe risks associated with vascular and arterial surgery.

BRIEF SUMMARY OF THE INVENTION

The subject technology is illustrated, for example, according to variousaspects described below. Various examples of aspects of the subjecttechnology are described as numbered clauses (1, 2, 3, etc.) forconvenience. These are provided as examples, and do not limit thesubject technology. It is noted that any of the dependent clauses may becombined in any combination, and placed into a respective independentclause. The other clauses can be presented in a similar manner.

1. A system for treating disease involving branching vessels of amammal, comprising:

a main graft assembly (i) having a lumen permitting fluid flowtherethrough, and (ii) configured to expand within, and contact a wallof, a main vessel of a mammal; and

a branch graft assembly comprising:

-   -   a branch cover (i) having a lumen (cover lumen) permitting fluid        flow therethrough; and (ii) configured to expand within, and        contact a wall of, a branch vessel that branches from the main        vessel;    -   an expandable stent (branch stent) extending within the cover        lumen; and    -   a branch sheath (i) extending between the branch stent and the        cover lumen, and (ii) constraining radial expansion of the        branch stent within the cover lumen.

2. The system of clause 1, wherein the branch sheath at least partiallysurrounds the branch stent.

3. The system of clause 1, wherein a distal portion of the branch stentis coupled to a distal portion of the branch cover.

4. The system of clause 3, wherein the branch stent is coupled to thebranch cover along at least part of a perimeter of the branch cover.

5. The system of clause 1, wherein distal movement of the branch sheathwithin the branch cover is inhibited by a coupling of the branch stentto the branch cover.

6. The system of clause 5, wherein the coupling is of a distal portionof the branch stent to a distal portion of the cover.

7. The system of clause 1, wherein the branch stent is self-expanding.

8. The system of clause 1, further comprising a delivery catheter (a)configured to be placed into the main vessel and (b) through which themain graft assembly is configured to extend.

9. The system of clause 8, further comprising an outer sheath throughwhich the delivery catheter extends.

10. The system of clause 8, wherein the branch sheath extends throughboth an aperture in the catheter and an aperture in the main graftassembly.

11. The system of clause 8, wherein the branch sheath extends through anaperture in the catheter.

12. The system of clause 11, wherein the branch graft assembly ismovable within the aperture.

13. The system of clause 11, wherein the aperture comprises alongitudinal groove in the catheter.

14. The system of clause 1, wherein the main graft assembly is coupledto the branch graft assembly.

15. The system of clause 1, wherein the branch sheath extends outsidethe main graft assembly.

16. The system of clause 1, wherein the branch sheath extends within themain graft assembly and into the branch cover through an aperture in themain graft assembly.

17. The system of clause 1, wherein the branch graft assembly is coupledto the main graft assembly.

18. The system of clause 1, wherein the branch stent is configured toexpand radially against the branch cover upon release of the branchstent from the branch sheath by proximal movement of the branch sheath.

19. The system of clause 1, wherein the main graft assembly and thebranch graft assembly are configured to lie substantially parallel toeach other during delivery of the main graft assembly to the mainvessel, and wherein the branch graft assembly is configured such that,while a proximal portion of the assembly remains within and/or incontact with the main graft assembly, the distal portion of the assemblymoves away from the main graft assembly when the assembly isunconstrained by a sheath during delivery of the branch cover to thebranch vessel.

20. The system of clause 1, further comprising an elongate member(branch delivery member) configured to extend through the branch coverand into the branch vessel.

21. The system of clause 20, further comprising an anchoring member, ata distal portion of the branch delivery member, that expands in andengages the branch vessel to resist axial movement of the anchoringmember within the branch vessel.

22. The system of clause 1, wherein each of the main vessel and thebranch vessel comprises an artery or a vein.

23. The system of clause 1, wherein the main graft assembly comprises(a) a main stent that is expandable and (b) a main cover that at leastpartially surrounds the main stent.

24. The system of clause 23, wherein each of the main cover and thebranch cover comprises an impermeable or semipermeable fabric.

25. The system of clause 23, wherein the a main cover is coextensivewith the branch cover.

26. The system of clause 23, wherein the main cover is coupled to thebranch cover.

27. The system of clause 1, further comprising an elongate member (maindelivery member) configured to extend through the main graft assemblyinto the main vessel.

28. The system of clause 1, further comprising a pusher that extendswithin the branch sheath and is configured to resist proximal movementof the branch stent within the branch sheath when a distal end of thepusher contacts a proximal end of the branch stent.

29. The system of clause 21, wherein the anchoring member self-expandsupon release of the anchoring member from a lumen of a constrainingmember.

30. The system of clause 29, wherein the release of the anchoring memberoccurs by proximal movement of the constraining member relative to theanchoring member.

31. A method, of treating disease involving branching blood vessels of amammal, comprising: [0048] advancing distally into a first blood vesselof a mammal a main stent graft having a lumen permitting fluid flowtherethrough; [0049] expanding the main stent graft within, andcontacting a wall of, the main vessel; [0050] advancing through the mainvessel, and into a branch vessel that branches from the main vessel, abranch graft assembly comprising: [0051] a branch cover (i) having alumen (cover lumen) permitting fluid flow therethrough; [0052] anexpandable stent (branch stent) extending within the cover lumen; and[0053] a branch sheath (i) extending between branch stent and the coverlumen, and (ii) constraining radial expansion of the branch stent withinthe cover lumen; [0054] releasing the branch stent from within thebranch sheath, thereby permitting expansion of the branch stent andbranch cover such that the branch cover contacts a wall of the branchvessel.

32. The method of clause 31, wherein the branch sheath at leastpartially surrounds the branch stent.

33. The method of clause 31, wherein the releasing comprises moving thebranch sheath proximally.

34. The method of clause 33, further comprising withdrawing the branchsheath from the mammal.

35. The method of clause 33, wherein the advancing of the main stentgraft, the advancing of the branch graft assembly, and withdrawing ofthe branch sheath from the mammal after the releasing all occur througha single opening in skin of the mammal.

36. The method of clause 31, wherein the main stent graft and the branchgraft assembly are advanced together into the main vessel within adelivery catheter.

37. A system for treating disease involving branching vessels of amammal, comprising:

a main cover (i) having a main lumen permitting fluid flow therethrough,and (ii) configured to expand in, and contact a wall of, a main vesselof a mammal; and

a branch cover (i) having a branch lumen in fluid communication with themain lumen, and (ii) configured to expand in, and contact a wall of, abranch vessel that branches from the main vessel;

wherein the branch cover is coupled to the main cover at an opening inthe main cover, and the branch cover has a longitudinal length extendingfrom the opening to a distal end of the branch cover;

wherein the opening has a larger area than does a cross section of thebranch lumen that is less than 80% of the length away from the opening.

38. The system of clause 37, wherein (i) the branch vessel is firstbranch vessel, (ii) the branch cover is a first branch cover; and (iii)the branch lumen is first branch lumen; and

further comprising a second branch cover (i) having a second branchlumen, in fluid communication with the main lumen, and (ii) configuredto expand in, and contact a wall of, a second branch vessel thatbranches from the main vessel.

39. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 70% of thelength away from the opening.

40. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 60% of thelength away from the opening.

41. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 50% of thelength away from the opening.

42. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 40% of thelength away from the opening.

43. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 30% of thelength away from the opening.

44. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 25% of thelength away from the opening.

45. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 20% of thelength away from the opening.

46. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 15% of thelength away from the opening.

47. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 10% of thelength away from the opening.

48. The system of clause 37, wherein the opening has a larger area thandoes a cross section of the branch lumen that is less than 5% of thelength away from the opening.

49. The system of any of clauses 37-47, wherein the opening area is atleast 10% larger than the area of the cross section of the branch lumen.

50. The system of any of clauses 37-47, wherein the opening area is atleast 20% larger than the area of the cross section of the branch lumen.

51. The system of any of clauses 37-47, wherein the opening area is atleast 30% larger than the area of the cross section of the branch lumen.

52. The system of any of clauses 37-47, wherein the opening area is atleast 40% larger than the area of the cross section of the branch lumen.

53. The system of any of clauses 37-47, wherein the opening area is atleast 50% larger than the area of the cross section of the branch lumen.

54. The system of any of clauses 37-47, wherein the opening area is atleast 60% larger than the area of the cross section of the branch lumen.

55. The system of any of clauses 37-47, wherein the opening area is atleast 70% larger than the area of the cross section of the branch lumen.

56. The system of any of clauses 37-47, wherein the opening area is atleast 80% larger than the area of the cross section of the branch lumen.

57. The system of any of clauses 37-47, wherein the opening area is atleast 90% larger than the area of the cross section of the branch lumen.

58. The system of any of clauses 37-47, wherein the opening area is atleast 100% larger than the area of the cross section of the branchlumen.

59. The system of any of clauses 37-47, wherein the opening area is atleast 120% larger than the area of the cross section of the branchlumen.

60. The system of any of clauses 37-47, wherein the opening area is atleast 150% larger than the area of the cross section of the branchlumen.

61. The system of any of clauses 37-47, wherein the opening area is atleast 180% larger than the area of the cross section of the branchlumen.

62. The system of any of clauses 37-47, wherein the opening area is atleast 200% larger than the area of the cross section of the branchlumen.

63. The system of any of clauses 37-61, wherein fluid flow through themain lumen is substantially along a longitudinal axis of the main lumen,and the opening has a dimension along the longitudinal axis that isgreater than a dimension of the opening along an axis transverse to thelongitudinal axis.

64. The system of clause 62, wherein the transverse axis isperpendicular to the longitudinal axis.

65. The system of clause 37, further comprising:

an expandable stent extending within the main lumen; and

an expandable stent extending within the branch lumen.

66. The system of clause 37, wherein the branch cover is sealed to themain cover by at least one of sewing, thermal bonding, or gluing.

67. The system of clause 37, wherein the branch cover is integrallyformed with the main cover.

68. The system of clause 37, wherein the branch cover and the main covercomprise a fabric.

69. The system of clause 37, wherein a junction between the branch coverand the main cover comprises a seal preventing blood cells from passingtherethrough.

70. A system for treating disease involving branching vessels of amammal, comprising:

a main cover (i) having a main lumen permitting fluid flow therethrough,and (ii) configured to expand in, and contact a wall of, a main vesselof a mammal; and

first and second branch covers, each (i) branching from the main coverat a respective cover ostium, (ii) having a respective branch lumen influid communication with the main lumen, and (ii) being configured toexpand in, and contact a wall of, a respective branch vessel thatbranches from the main vessel at a respective vessel ostium;

wherein the main and branch covers are configured such that, after themain cover is expanded in the main vessel, and after the two branchcovers are expanded in the respective branch vessels such that (i) thefirst cover ostium is substantially aligned with the first vesselostium, and (ii) the second cover ostium is not substantially alignedwith the second vessel ostium, then blood flows from the main cover intoeach of the branch covers.

71. The system of clause 73, wherein the main cover and the two branchcovers each comprises fabric, and, prior to insertion of the main coverinto the main vessel, the fabric of each of the two branch covers iscontinuous with, integrally formed with, or permanently attached to, thefabric of the main cover.

72. The system of clause 73, wherein (i) the main cover and the twobranch covers each comprises a fabric, (ii) the second branch cover hasa longitudinal length extending from the second cover ostium to a distalend of the second branch cover, and (iii) a cross sectional area of thesecond branch lumen at the second cover ostium is larger than is a crosssectional area of the second branch lumen that is less than 80% of thelength away from the opening.

73. The system of clause 73, wherein (i) the second branch covercomprises a fabric, and (ii) a cross sectional dimension of the secondbranch cover decreases from the second cover ostium toward a distal endof the second branch cover.

74. The system of clause 73, wherein (i) the second branch cover tapersfrom the second cover ostium toward a distal end of the second branchcover.

75. The system of any of the above clauses, wherein the main vesselcomprises an aorta, and each of any of the branch vessels comprises arenal artery.

76. A method for treating disease involving branching vessels of amammal, comprising:

inserting into a main vessel a main cover (i) having a main lumenpermitting fluid flow therethrough and (ii) configured to expand in, andcontact a wall of, the main vessel;

inserting into a first branch vessel, that branches from the main vesselat a first vessel ostium, a first branch cover that (i) branches fromthe main cover at a first cover ostium, (ii) has a first branch lumen influid communication with the main lumen, and (ii) is configured toexpand in, and contact a wall of, the first branch vessel;

inserting into a second branch vessel, that branches from the mainvessel at a second vessel ostium, a second branch cover that (i)branches from the main cover at a second cover ostium, (ii) has a secondbranch lumen in fluid communication with the main lumen, and (ii) isconfigured to expand in, and contact a wall of, the second branchvessel;

wherein, after the inserting of the first and second branch covers, (i)the first cover ostium is substantially aligned with the first vesselostium, (ii) the second cover ostium is not substantially aligned withthe second vessel ostium, and (iii) blood flows from the main cover intoeach of the first and second branch covers.

77. The method of clause 69, wherein the main cover and the two branchcovers each comprises fabric, and, prior to insertion of the main coverinto the main vessel, the fabric of each of the two branch covers iscontinuous with, integrally formed with, or permanently attached to, thefabric of the main cover.

78. A method for treating disease involving branching vessels of amammal, comprising:

inserting into a main vessel a main cover (i) having a main lumenpermitting fluid flow therethrough and (ii) configured to expand in, andcontact a wall of, the main vessel;

inserting into each of first and second branch vessels, each branchingfrom the main vessel at a respective vessel ostium, a respective branchcover that (i) branches from the main cover at a respective coverostium, (ii) has a respective branch lumen in fluid communication withthe main lumen, and (ii) is configured to expand in, and contact a wallof, the respective branch vessel;

wherein, after the inserting of the two branch covers, (i) the firstcover ostium is substantially aligned with the first vessel ostium, (ii)the second cover ostium is not substantially aligned with the secondvessel ostium, and (iii) blood flows from the main cover into each ofthe first and second branch covers.

79. The method of clause 71, wherein the main cover and the two branchcovers each comprises fabric, and, prior to insertion of the main coverinto the main vessel, the fabric of each of the two branch covers iscontinuous with, integrally formed with, or permanently attached to, thefabric of the main cover.

80. The method of any of the above method clauses, wherein the mainvessel comprises an aorta, and each of any of the branch vesselscomprises a renal artery.

Additional features and advantages of the subject technology will be setforth in the description below, and in part will be apparent from thedescription, or may be learned by practice of the subject technology.The advantages of the subject technology will be realized and attainedby the structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the subject technology asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the subject technology and are incorporated in andconstitute a part of this specification, illustrate aspects of thesubject technology and together with the description serve to explainthe principles of the subject technology.

FIG. 1 depicts a main vessel with a main delivery member therein and abranching vessel with a branch delivery member therein.

FIG. 2 depicts an endograft delivery system, according to one aspect ofthe subject technology.

FIG. 3 depicts an endograft delivery system with an outer sheathwithdrawn proximally, according to one aspect of the subject technology.

FIG. 4 depicts an endograft delivery system positioned in the vicinityof a branch vessel, according to one aspect of the subject technology.

FIG. 5 depicts an endograft delivery system with a delivery catheterwithdrawn proximally, according to one aspect of the subject technology.

FIG. 6 depicts a deployed main graft assembly, accordingly to one aspectof the subject technology.

FIG. 7 depicts a branch graft assembly being deployed by an endograftdelivery system, according to one aspect of the subject technology.

FIG. 8 depicts a branch graft assembly being deployed by an endograftdelivery system, according to one aspect of the subject technology.

FIG. 9 depicts a deployed branch graft assembly, according to one aspectof the subject technology.

FIG. 10 depicts a deployed endograft, according to one aspect of thesubject technology.

FIG. 11 depicts a cross section of a branch graft assembly, according toone aspect of the subject technology.

FIG. 12 depicts a partial cross section view of an endograft deliverysystem, according to one aspect of the subject technology.

FIG. 12A depicts a cross section side view of an endograft deliverysystem, according to one aspect of the subject technology.

FIG. 13 depicts a detailed cross section of an endograft deliverysystem, according to one aspect of the subject technology.

FIGS. 14-18 depict a branch endograft fabric “cover” that branches froma main endograft fabric “cover” and tapers from a relatively widecross-sectional dimension at the branch ostium to a narrowercross-sectional dimension along more distal portions of the branchendograft's axial length.

FIG. 19 depicts a branch endograft assembly according to the subjecttechnology, with the main cover placed in the aorta, and two branchcovers cover placed in bilateral renal arteries having axiallyasymmetric ostia.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth to provide a full understanding of the subject technology. It willbe apparent, however, to one ordinarily skilled in the art that thesubject technology may be practiced without some of these specificdetails. In other instances, well-known structures and techniques havenot been shown in detail so as not to obscure the subject technology.Like components are labeled with identical element numbers for ease ofunderstanding.

Aortic aneurysms are a weakening in the wall of the aorta which causesthis large blood vessel to expand. At various diameters, thispotentially can cause this vessel to rupture causing significant bloodloss and death. The aorta is responsible for transporting blood from theheart to the various organs in the body. Various organs (i.e., liver,lungs, kidneys, brain) are supplied blood by branches from the aortawhich are of various sizes and length. At times, aneurysms may be soextensive as to include or involve a branch or branches of blood vesselswhich supply blood to various organs.

Historically, the treatment of aortic aneurysms involved the surgicalexcision of the aneurysm. If one or more of the important organ brancheswas involved, a “side branch,” made of various materials, was typicallyattached to the larger main bypass graft by sewing the smaller caliber“side branch” graft to the main bypass graft.

Grafts used in endograft repair of aortic aneurysms, a minimallyinvasive technique, are typically inserted into a femoral artery(although they could be inserted into another artery, such as thesubclavian) and moved to the area of the aneurysm using various methodsof deployment. Once in position, the graft is deployed at the aneurysmsite, thereby eliminating blood flow into the aneurysm and eliminatingthe danger of rupture. If the aneurysm, however, involves one of themajor organ branches, using the endovascular technique described abovebecomes more difficult.

Conventional methods for treating aortic aneurysms that involve majororgan branches include the use of modular aortic endografts. Modularaortic endografts are constructed with what are called “fenestrations”or small “holes” or “windows” in the main body of the endograft whichcoincide with the take off or origin of the involved branch of theaorta. Through these “fenestrations,” smaller endografts are deployed soas to continue blood flow to the major organ and assure exclusion of theaneurysm. The smaller endografts that are deployed through the“fenestrations” are prone to leak at the attachment point, dislodge,and/or migrate downstream. Any one of these situations can create alarge “endoleak” which may repressurize the aneurysm sac and causerupture.

In addition, by excluding aneurysms from blood flow with a modular graftin an attempt to “cure” the condition, the morphology of the aorta canchange. Post-grafting aortic changes may include shrinkage, changes inshape, curvature, and/or size. The changes may generate significantstresses on the graft and cause dislodgement of not only the entireendograft, but also of any modular limb or side branch. Such dislodgmentmay cause the complete failure of the endograft, thereby resulting in apossible rupture of the aneurysm.

Although one-piece bifurcated grafts largely eliminate leakage and graftfailure at the suture or juncture site associated with two piecebifurcated grafts that join together two separate grafts to form thebifurcated graft, past delivery methods for one-piece bifurcated graftshave been suboptimal, often requiring access to both limbs forunsheathing bifurcated grafts.

The implantable device of the subject technology solves some or all ofthe foregoing problems by using a one piece, “non-modular” branchedendograft that is not prone to separation or leakage. The non-modularbranched endograft provides almost immediate blood flow to theinterested organ and significantly improves the integrity of the entireendograft by essentially eliminating all likelihood that the endograftmay leak, migrate, or be disrupted. The longevity of the non-modularbranched endograft is thus improved, ensuring the success of theprocedure. In addition, although the branched endograft of the subjecttechnology may be constructed as a one-piece endograft, it is understoodthat the branched endograft may be constructed from modular componentsthat are coupled to each other.

FIG. 1 illustrates a schematic representation of a first blood vessel101 and a second blood vessel 102, the second blood vessel 102 branchingfrom the first blood vessel 101. The main vessel 101 and branch vessel102 may comprise an artery or a vein. For example, the main vessel 101may be a thoracic or abdominal aorta and the branch vessel 102 may be avisceral artery. An aneurysm 103 is illustrated adjacent the main vessel101 and the branch vessel 102. As will be explained, in more detailbelow, the branched endograft 300, as shown in FIG. 10, may be used tospan the aneurysm 103.

Referring to FIG. 10, the branched endograft 300 may be used fortreating disease involving branching vessels 100 of a mammal. Thebranched endograft 300 may include a main graft assembly 310 and one ormore branch graft assemblies 320.

The main graft assembly 310 may include a main cover 312 and a mainstent 314. The main stent 314 may be expandable and the main cover 312may at least partially surround the main stent 314.

The main stent 314 may comprise a tubular wire support structure thatmay be configured to be expanded via an internal expanding device (e.g.,a balloon) or may be wholly or partially self expandable. For example, aself expandable tubular support may be formed from a shape memory alloythat can be deformed from an original, heat-stable configuration to asecond heat-unstable configuration. The main stent 314 may be formedfrom a piece of metal tubing that is laser cut. The main stent 314 maycomprise one or more wires and other self-expandable configurationsknown to those of skill in the art. Self expandable tubular structuresmay conveniently be formed with a series of axially adjacent segments.Each segment generally comprises a zig-zag wire frame having a pluralityof apexes at its axial ends, and wire struts extending therebetween. Theopposing apexes of adjacent segments may be connected in some or allopposing apex pairs, depending upon the desired performance. In anotherexample, one or more of the individual segments may be separated fromadjacent segments and retained in a spaced apart, coaxial orientation bythe main cover 312 or other graft material. The main stent 314 need notextend through the entire axial length of the main cover 312.

Further referring to FIG. 10, the main cover 312 may have a generallytubular body having a distal end 311 which defines a distal opening, anda proximal end 315 which defines a proximal opening. As used herein, theterms proximal and distal are defined relative to a deployment catheter,such that the distal end 311 is positioned further away from thedeployment catheter than the proximal end 315. The main cover 312 may bemanufactured from an impermeable or semipermeable fabric and may beformed from any of a variety of synthetic polymeric materials, orcombinations thereof, including ePTFE, PE, PET, Urethane, Dacron, nylon,polyester or woven textiles.

The main cover 312 may have a lumen to permit fluid flow therethroughand may be configured to expand within, and contact a wall of, the mainvessel 101. In one aspect, the material of the main cover 312 may besufficiently porous to permit ingrowth of endothelial cells, therebyproviding more secure anchorage of the main cover 312 and potentiallyreducing flow resistance, sheer forces, and leakage of blood around themain cover 312. The porosity characteristics of the main cover 312 maybe either homogeneous throughout the axial length of the main cover 312,or may vary according to the axial position of the main cover 312. Forexample, it may be advantageous to configure the distal end 311 and theproximal end 315 of the main cover 312, which seat against the mainvessel wall 101, to encourage endothelial growth, or, to permitendothelial growth to infiltrate portions of the main cover 312 in orderto enhance anchoring and minimize leakage. Because anchoring may be lessof an issue, the central portion of the main cover 312, which may spanthe aneurysm, may be configured to maximize lumen diameter andminimizing blood flow through the main cover 312 wall and therefore, mayeither be generally nonporous, or provided with pores of relativelylower porosity.

Referring to FIG. 11, the branch graft assembly 320 may include a branchcover 322, a branch stent 324, and a branch sheath 326.

The branch cover or cover lumen 322 may comprise a generally tubularbody having a proximal end 325 which defines a proximal opening, and adistal end 321 which defines a distal opening. The branch cover 322 maybe manufactured from an impermeable or semipermeable fabric and may beformed from any of a variety of synthetic polymeric materials, orcombinations thereof, including ePTFE, PE, PET, Urethane, Dacron, nylon,polyester or woven textiles.

The branch cover 322 may have a lumen to permit fluid flow therethroughand may be configured to expand within, and contact a wall of, thebranch vessel 102. In one aspect, the material of the branch cover 322may be sufficiently porous to permit ingrowth of endothelial cells,thereby providing more secure anchorage of the branch cover 322 andpotentially reducing flow resistance, sheer forces, and leakage of bloodaround the branch cover 322. The porosity characteristics of the branchcover 322 may be either homogeneous throughout the axial length of thebranch cover 322, or may vary according to the axial position of thebranch cover 322. For example, it may be advantageous to configure adistal end 321 of the branch cover 322, which seats against the branchvessel wall 102, to encourage endothelial growth, or, to permitendothelial growth to infiltrate portions of the branch cover 322 inorder to enhance anchoring and minimize leakage. Because anchoring maybe less of an issue, the central or proximal portion of the branch cover322, which may span the aneurysm, may be configured to maximize lumendiameter and minimizing blood flow through the branch cover 322 wall andtherefore, may either be generally nonporous, or provided with pores ofrelatively lower porosity.

Referring again to FIG. 10, the branch graft assembly 320 may be coupledto the main graft assembly 310. Specifically, the branch cover 322 maybe coupled to the main cover 312. For example, the proximal end 325 ofthe branch cover 322 may be coupled to the main cover 312 at a region330 that is intermediate of the proximal end 315 and the distal end 311of the main cover 312. The coupling region 330 may be configured toallow fluid communication between the lumen of the main cover 312 andthe lumen of the branch cover 322 via an aperture, thereby making themain cover 312 and the branch cover 322 integral or coextensive, i.e.,one piece and non-modular. The coupling region 330 may also beconfigured to allow the branch cover 322 to articulate and permitsufficient flexibility between the main cover 312 and the branch cover322 such that the branch cover 322 may be placed within the branchvessel 102 while the main cover 312 is positioned within the main vessel101

Referring to FIG. 11, the branch stent 324 may comprise an expandablestent that extends within the branch cover 312. The branch stent 324 maybe configured to expand radially against the branch cover 312 uponrelease of the branch stent 324 from the branch sheath 326, as discussedfurther below, by proximal movement of the branch sheath 326. Afterdeployment, the branch stent 324 may support the branch cover 322 in thebranch vessel 102 such that the branch cover 322 makes sufficientcontact against the branch vessel wall 102.

The branch stent 324 may comprise a tubular wire support structure thatmay be configured to be expanded via an internal expanding device (e.g.,a balloon) or may be wholly or partially self expandable. For example, aself expandable tubular support may be formed from a shape memory alloythat can be deformed from an original, heat-stable configuration to asecond heat-unstable configuration. The branch stent 324 may be formedfrom a piece of metal tubing that is laser cut. The branch stent 324 maycomprise one or more wires and other self-expandable configurationsknown to those of skill in the art. Self expandable tubular structuresmay conveniently be formed with a series of axially adjacent segments.Each segment generally comprises a zig-zag wire frame having a pluralityof apexes at its axial ends, and wire struts extending therebetween. Theopposing apexes of adjacent segments may be connected in some or allopposing apex pairs, depending upon the desired performance. In anotherexample, one or more of the individual segments may be separated fromadjacent segments and retained in a spaced apart, coaxial orientation bythe branch cover 322 or other graft material. The branch stent 324 neednot extend through the entire axial length of the branch cover 322.

A distal portion of the branch stent 324 may be coupled or attached to adistal portion of the branch cover 322 along at least part of aperimeter of the branch cover 322. Coupling 323 of the branch stent 324to the branch cover 322 may be achieved by clipping, sewing, bonding,gluing, heat fusing, or other coupling methods as may be known by aperson of ordinary skill

The branch sheath 326 may comprise a flexible tubular sheath extendingbetween the branch stent 324 and the branch cover 322. The branch sheath326 may be configured to compress or constrain the radial expansion ofthe branch stent 324 within the branch cover 322 by at least partiallysurrounding the branch stent 324. The branch sheath 326 may beconfigured to extend within and through the main graft assembly 310,toward and into the branch graft assembly 320, via the aperture of thecoupling region 330, as shown in FIGS. 6-9.

Suitable dimensions for the main cover 312 and branch cover 322 can bereadily selected taking into account the natural anatomical dimensionsof the treatment area, i.e., the main vessel 101 and the branch vessel102. For example, for treatment of an aortic aneurysm, account of thenatural anatomical dimensions in the thoracic aorta and its principalbranches (i.e., the innomate artery, left carotid and subclavianarteries) would be taken. In this example, the main cover 312 will havea fully expanded diameter within the range of from about 20 mm to about50 mm, and a length within the range of from about 5 cm to about 20 cmfor use in the descending aorta. Lengths outside of these ranges may beused, for example, depending upon the length of the aneurysm to betreated, the tortuosity of the aorta in the affected region and theprecise location of the aneurysm. Shorter lengths may be desirable forthe main cover 312 when treating aneurysms in the ascending aorta or theaortic arch as will be appreciated by those of skill in the art.

The branch cover 322 for use in the subclavian artery will generallyhave a length within the range of from about 10 mm to about 20 mm, and afully expanded diameter within the range of from about 2 cm to about 10cm. Both the main cover 312 and the branch cover 322 will preferablyhave a fully expanded diameter in an unconstrained state which is largerthan the inside diameter of the vessel within which they are to bedeployed, in order to maintain positive pressure on the vessel wall.

The minimum length for the main cover 312 will be a function of the sizeof the aneurysm. Preferably, the axial length of the main cover 312 willexceed the length of the aneurysm, such that a seating zone is formed ateach end of the main cover 312 within which the main cover 312 overlapswith healthy vascular tissue beyond the proximal and distal ends of theaneurysm.

In one aspect, the main graft assembly 310 and the branch graft assembly320 may be configured to lie substantially parallel to each other duringdelivery of the main graft assembly 310 to the main vessel 101. Asdescribed further below, upon deployment of the branch graft assembly320, a proximal portion of the branch graft assembly 320 may remainwithin and/or in contact with the main graft assembly 310 while a distalportion of the branch graft assembly 320 may move away from the maingraft assembly 310, as shown in FIGS. 3-5.

FIG. 12 is a partial cross-section side view of an endograft deliverysystem 200, which can be used to deploy the main graft assembly 310 andthe branch graft assembly 320 described above. The main graft assembly310 and the branch graft assembly 320 may be delivered to a treatmentsite using the delivery system 200, which allows for retrogradedeployment of the branched endograft 300 from the femoral artery. Otherdistal vessels, however, may be utilized for deployment.

The delivery system 200 may comprise an elongate flexiblemulti-component structure comprising an outer sheath 210, a deliverycatheter 220, a pusher 240, a main delivery member 201, a branchdelivery member 202, and an anchoring member 203.

Referring to FIG. 13, the outer sheath 210 may be configured to compressor constrain the expansion of the branch graft assembly 320 by at leastpartially surrounding the branch graft assembly 320. The outer sheath210 may also be configured to at least partially surround the deliverycatheter 220. The outer sheath 210 may be manufactured frombiocompatible materials and may be provided with a proximal hub orvalve.

In one aspect, a distal end of the outer sheath 210 may have a cutout212A, longitudinal protrusion 212B (as shown in FIG. 2), or aperture toprovide clearance for the branch delivery member 202 to extendtherethrough, as shown in FIG. 13. In another aspect, the outer sheath210 may include a stop (not shown) configured to limit distal movementof the outer sheath 210 with respect to the delivery catheter 220 suchthat a gap 212A may be formed between the outer sheath 210 and thedelivery catheter 220 to provide sufficient clearance for the branchdelivery member 202 to extend therethrough. In one aspect, theprotrusion 212B may provide an area for the branch graft assembly 320 toreside within. As will be explained in detail below, proximal retractionof the outer sheath 210 with respect to the delivery catheter 220 willdeploy the branch graft assembly 320. Accordingly, the outer sheath 210may be axially movably positioned with respect to the delivery catheter220.

The delivery catheter 220 may be configured to extend through the outersheath 210 and deploy the main graft assembly 310. The delivery cathetermay comprise a delivery sheath 220 and an inner elongate member 230. Thedelivery sheath 220 and the elongate member 230 may be manufactured frombiocompatible materials. The main graft assembly 310 may be positionedin a compressed or reduced diameter state within the delivery sheath220, between the delivery sheath 220 and the elongate member 230. Aswill be explained in detail below, proximal retraction of the deliverysheath 220 with respect to the elongate member 230 will deploy the maingraft assembly 310. Accordingly, the delivery sheath 220 may be axiallymovably positioned within the outer sheath 210.

The delivery sheath 220 may be configured to at least partially surroundthe main graft assembly 310 and keep the main graft assembly 310 in acompressed configuration during passage through various vessels to thetreatment site 100. The delivery sheath 220 may include a plurality ofreinforcing ribs or supports to further aid in maintaining the maingraft assembly 310 in the compressed configuration.

A distal end of the delivery sheath 220 may have an aperture,longitudinal slot or groove 222 to accommodate the branch graft assembly320 in a compressed configuration during passage through various vesselsto the treatment site 100. The groove 222 may also assist in minimizingthe diameter of the outer sheath 210 by accommodating the branch graftassembly 320 within the groove 222. In one aspect, the branch sheath 326may extend through the groove 222, as shown in FIG. 13.

The elongate member 230 may have a tapered distal tip to minimize damageto the vessel wall during passage through various vessels to thetreatment site. The elongate member 230 may extend within the deliverysheath 220 and may be configured to resist proximal and/or distalmovement of the main graft assembly 310 within the delivery sheath 220.For example, the elongate member 230 may have a circumferential rib 232configured to engage the proximal end 315 of the main graft assembly310. The elongate member 230 may have a lumen for allowing the maindelivery member 201 to extend therethrough. In one aspect, the elongatemember 230 may have an indent 234 for accommodating the branch sheath326, as shown in FIGS. 6-9, 12 and 12A.

The main delivery member 201 may be a guide wire configured to extendthrough the, outer sheath 210, the delivery catheter 220, and the maingraft assembly 310, into the main vessel 101.

The branch delivery member 202 may be a guide wire configured to extendthrough the outer sheath 210, the delivery catheter 220, the branchcover 322, the branch stent 324, and the branch sheath 326, and thepusher 240, into the branch vessel 102.

Referring to FIGS. 11 and 13, the pusher 240 may extend within thebranch sheath 326 and may be configured to resist proximal movement ofthe branch stent 324 within the branch sheath 326. The pusher 240 maycomprise a flexible tubular member having a distal end that isconfigured to engage a proximal end of the branch stent 324 to therebyprevent the compressed branch stent 324 from moving proximally and aidin deployment of the branch stent 324 as the branch sheath 326 is movedproximally. The pusher 240 may also include a lumen for allowing thebranch delivery member 202 to extend therethrough.

Referring to FIG. 1, the anchoring member 203 may be disposed at adistal portion of the branch delivery member 202. The anchoring member203 is configured to expand in and engage the branch vessel 102 toprovide an atraumatic tip and resist axial movement of the anchoringmember 203 within the branch vessel 102, thereby enabling the branchdelivery member 202 to maintain its position within the branch vessel102 as the branch cover 322 is maneuvered and deployed in the branchvessel 102, as further described below. The anchoring member 203 isconfigured to engage the branch vessel 102 by applying gentle outwardpressure onto the inner surface of the branch vessel 102.

The anchoring member 203 enables deployment of the branch graft assemblyin an end organ vessel, such as the renal, superior or inferiormesenteric, celiac, splenic, or hepatic arteries, or biliary orpancreatic ducts. Serving as an atraumatic tip, the anchoring member 203helps prevent the branch delivery member 202 from puncturing an endorgan perfused by the artery into which the anchoring member 203 isinserted.

The anchoring member 203 may be wholly or partially self expandable,e.g., via application of heat or upon release of the anchoring member203 from a lumen of a constraining member, such as a sheath (not shown).In the later example, the anchoring member 203 may be released byproximal movement of the constraining member relative to the anchoringmember 203. The anchoring member 203 may be constructed of multipleflexible curved wire struts so as to take a oblong form. In analternative embodiment, the anchoring member 203 be expanded via aninternal expanding device (e.g., a balloon).

The outer sheath 210, the delivery catheter 220, and the othercomponents of the delivery system 200 can be manufactured in accordancewith any of a variety of techniques well known in the cathetermanufacturing field. Extrusion of tubular catheter body parts frommaterial such as Polyethylene, PEBAX, PEEK, nylon and others is wellunderstood. Suitable materials and dimensions can be readily selectedtaking into account the natural anatomical dimensions of the treatmentsite, together with the dimensions of the desired implant andpercutaneous or other access site.

A technique for deploying the branched endograft 300 using the deliverysystem 200 for treating disease involving branching blood vessels of amammal will now be discussed with reference to FIGS. 1-9. The treatmentmay, for example, comprise treating an aortic aneurysm. As shown in FIG.1, two guide wires, the main delivery member 201 and the branch deliverymember 202 are used for the deployment of the main graft assembly 310and the branch graft assembly 320. The main delivery member 201 may beused to guide the outer sheath 210, together with the delivery catheter220 and the branched endograft 300, to the main vessel 101, which may beintroduced through an arterial catheter. The branch delivery member 202may be used for the deployment of the branch cover 322 into the branchvessel 102.

The main delivery member 201 and the branch delivery member 202 maycomprise a standard 0.035″ diameter guide wire. The main delivery member201 and the branch delivery member 202 may be introduced, for example,through a percutaneous puncture via a sheath, and advanced superiorlytowards the aneurysm 103 and the treatment site 100. In one embodiment,the percutaneous puncture is formed on the femoral artery. The maindelivery member 201 is preferably positioned across the aneurysm andinto the main vessel 101. The branch delivery member 202 is preferablypositioned in the branch vessel 102.

The branch delivery member 202, including the anchoring member 203, maybe introduced through a catheter, which constrains or compresses theanchoring member 203 until it is positioned correctly in the branchvessel 102. The catheter or constraining member is then retracted, viaproximal movement of the constraining member relative to the anchoringmember 203, to allow the anchoring member 203 to gently expand andengage the branch vessel 102.

An advantage of the subject technology is that it permits delivery andsubsequent deployment (by unsheathing) of the branch graft assembly 320and the main graft assembly 310 into blood vessels via a single vascularaccess puncture. There is no need to use a second vessel puncture tounsheath either graft assembly.

Referring to FIG. 2, after the main delivery member 201 and the branchdelivery member 202 are in position, the main delivery member 201 andthe branch delivery member 202 are threaded through the appropriatelumens in the delivery system 200. For example, as described above, themain delivery member 201 extends through at least the lumen of theelongate member 230 and the branch delivery member 203 extends at leastthrough the cutout 212A (as shown in FIG. 13) or longitudinal protrusion212B of the outer sheath 210 and the lumen of the pusher 240 (as shownin FIG. 11).

The outer sheath 210, together with the delivery catheter 220 and thebranched endograft 300, may then be advanced over the main deliverymember 201 until the distal end of the delivery catheter 220 ispositioned at or near the treatment site 100. During this step, theouter sheath 210 surrounds the delivery catheter 220 and houses the maingraft assembly 310 and the branch graft assembly 320.

As shown in FIG. 3, once the distal end of the delivery catheter 220 isin the vicinity of the branch vessel 102, the branch graft assembly 320may be deployed. The branch graft assembly 320 may be deployed byproximally withdrawing the outer sheath 210, thereby exposing thedelivery catheter 220 and unconstraining the distal portion of thebranch graft assembly 320 to allow the branch graft assembly 320 toarticulate. In one aspect, the groove 222 provides the branch graftassembly 320 with sufficient clearance as to enable the distal portionof the branch graft assembly to be movable within the groove 222.

The coupling region 330 allows the branch graft assembly 320 toarticulate and permits sufficient flexibility between the main graftassembly 310 and the branch graft assembly 320 such that the branchgraft assembly 320 may be positioned within the branch vessel 102 whilethe main graft assembly 310 is positioned within the main vessel 101.

Referring to FIG. 4, as the delivery system 200 is advanced using themain delivery member 101, the branch graft assembly 320 is guided by thebranch delivery member 202 into the branch vessel 102.

Referring to FIG. 5, once the delivery catheter 220 is in the deploymentlocation, the delivery sheath 220 may be proximally withdrawn therebyallowing the main graft assembly 310 to expand within the main vessel101. Further proximal retraction of the delivery sheath 220 exposes themain graft assembly 310 allowing it to expand, spanning at least aportion of the aneurysm 103. Referring to FIG. 6, in one aspect,expansion of the main graft assembly 310 may further push the branchgraft assembly 320 into the branch vessel 102.

Referring to FIG. 7, after deployment of the main graft assembly 310,the branch sheath 326, which extends outside of the main graft assembly310 and within the branch graft assembly 320, may be proximallywithdrawn to thereby allow the branch stent 324 to expand radiallywithin and against the branch cover 322. Expansion of the branch stent324 causes the branch cover 322 to also expand within the branch vessel102. Referring to FIG. 8, further proximal retraction of the branchsheath 326 exposes the branch stent 324 allowing both the branch cover322 and the branch stent 324 to expand in the branch vessel 102. Thepusher 240 resists proximal movement of the branch stent 324 duringretraction of the branch sheath 326. In addition, because the branchstent 324 is coupled 323 to distal end 321 of the branch cover 322, asshown in FIG. 11, the branch stent 324 is maintained in position.Further, distal movement of the branch sheath 326 within the branchcover 322 is inhibited by the coupling 323 of the branch stent 324 tothe branch cover 322, as described above.

Referring to FIG. 9, after the branch cover 322 is deployed andsupported by the branch stent 324, the branch sheath 326, deliverysheath 220, and/or the elongate member 230 may be retracted into theouter sheath 210 for removal. With the main graft assembly 310 deployed,the delivery sheath 220 and/or the elongate member 230 may be proximallywithdrawn through the deployed main graft assembly 310. The deliverysystem 200 may thereafter be proximally withdrawn from the patient byway of the percutaneous access site.

The delivery system 200 and/or the branched endograft 300 may includeone or more radio opaque markers such that delivery system 200 and/orthe branched endograft 300 may be properly orientated with respect tothe anatomy. Any of a variety of techniques may be used to provide radioopaque markers, such as, for example, providing the components of thedelivery system 200 and/or the branched endograft 300 with bands orstaples made of radio opaque material or dispersing radio opaquematerial into the material that forms the components of the apparatus.

Although the branched endograft 300 and delivery system 200 have beendiscussed in the context of treating an aortic aneurysm that hascompromised one or more visceral branches of the thoracic or abdominalaorta, the branched endograft and delivery system may be used in anyanatomic region. For example, the branched endograft 300 and deliverysystem 200 may be used to treat not only vascular disease, but diseaseof other branching vessels of the body, such as bile ducts. End organbranch arteries may also be treated, such as the renal, superiormesenteric, celiac, splenic, or hepatic arteries.

FIGS. 14-18 depict a branch endograft fabric “cover” 422 that branchesfrom a main endograft fabric “cover” 412 and tapers from a relativelywide cross-sectional dimension at the branch ostium 430 to a narrowercross-sectional dimension along more distal portions 421 of the branchendograft's axial length. Due to fabric laxity in this illustrated case,the branch cover 422 can move relatively freely axially, radially, androtationally along its long axis to accommodate placement in a branchartery (e.g, a renal artery) whose ostium at a main vessel (e.g., theaorta) is axially and/or radially misaligned with the branch graftcover's ostium 430.

FIG. 19 depicts a branch endograft assembly according to the subjecttechnology, with the main cover (illustrated as a fabric) 412 placed inthe aorta 401, and two branch covers cover 422 and 423 (illustrated as afabric continuous with the main cover) placed in bilateral renalarteries (e.g., left renal artery 402 and right renal artery 403) havingsymmetric take-offs or ostia 432 and 433 (i.e., symmetric take-offpoints, or regions, relative to an axial length and/or radialorientation of the aorta). Having fabric of sufficient (redundant)length and flexibility, the left branch 422 cover is shown as axiallyshifted somewhat to permit blood to flow into the left renal artery 402,which has a more superiorly oriented ostium (or take-off) than that ofthe right renal artery 403.

The foregoing description is provided to enable a person skilled in theart to practice the various configurations described herein. While thesubject technology has been particularly described with reference to thevarious figures and configurations, it should be understood that theseare for illustration purposes only and should not be taken as limitingthe scope of the subject technology.

There can be many other ways to implement the subject technology.Various functions and elements described herein may be partitioneddifferently from those shown without departing from the scope of thesubject technology. Various modifications to these configurations willbe readily apparent to those skilled in the art, and generic principlesdefined herein may be applied to other configurations. Thus, manychanges and modifications may be made to the subject technology, by onehaving ordinary skill in the art, without departing from the scope ofthe subject technology.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Some of the stepsmay be performed simultaneously. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

Terms such as “top,” “bottom,” “front,” “rear” and the like as used inthis disclosure should be understood as referring to an arbitrary frameof reference, rather than to the ordinary gravitational frame ofreference. Thus, a top surface, a bottom surface, a front surface, and arear surface may extend upwardly, downwardly, diagonally, orhorizontally in a gravitational frame of reference.

A phrase such as an “aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations. Aphrase such as an aspect may refer to one or more aspects and viceversa. A phrase such as an “embodiment” does not imply that suchembodiment is essential to the subject technology or that suchembodiment applies to all configurations of the subject technology. Adisclosure relating to an embodiment may apply to all embodiments, orone or more embodiments. A phrase such an embodiment may refer to one ormore embodiments and vice versa.

Furthermore, to the extent that the term “include,” “have,” or the likeis used in the description or the claims, such term is intended to beinclusive in a manner similar to the term “comprise” as “comprise” isinterpreted when employed as a transitional word in a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically stated, but rather “one or more.” Theterm “some” refers to one or more. Underlined and/or italicized headingsand subheadings are used for convenience only, do not limit the subjecttechnology, and are not referred to in connection with theinterpretation of the description of the subject technology. Allstructural and functional equivalents to the elements of the variousconfigurations described throughout this disclosure that are known orlater come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and intended to beencompassed by the subject technology. Moreover, nothing disclosedherein is intended to be dedicated to the public regardless of whethersuch disclosure is explicitly recited in the above description.

What is claimed is:
 1. A system for treating disease involving branchingvessels of a mammal, comprising: a main cover (i) having a main lumenpermitting fluid flow therethrough, and (ii) configured to expand in,and contact a wall of, a main vessel of a mammal; and a branch cover (i)having a branch lumen in fluid communication with the main lumen, and(ii) configured to expand in, and contact a wall of, a branch vesselthat branches from the main vessel; wherein the branch cover is coupledto the main cover at an opening in the main cover, and the branch coverhas a longitudinal length extending from the opening to a distal end ofthe branch cover; wherein the opening has a larger area than does across section of the branch lumen that is less than 80% of the lengthaway from the opening.